Railway brake shoe

Abstract

An improved railway brake shoe member characterized by logitudinally tapered sidewalls of the brake shoe that provide adaptive response to braking under conditions of mis-alignment between the brake shoe member and the tread of a railway car wheel by facilitating wear-in of the mis-aligned brake shoe, thereby assuring brake shoe/wheel tread engagement and accordingly alleviating degradation of braking efficiency and undesirable thermal inputs to the wheel flange that otherwise results from such brake shoe mis-alignment.

I claim: 
     
       1. For frictionally braking a railway car wheel having a tread, a rim at one side of the tread and a flange at the other side of the tread, a brake shoe member comprising: (a) a backing plate to which a brake force is applied; and   (b) a brake shoe block affixed to said backing plate, said brake shoe block having first and second longitudinal sidewalls disposed lengthwise on opposite sides of a longitudinal centerline of said brake shoe block and opposing end walls, said sidewalls and said end walls delineating a braking face therebetween adapted to engage said wheel tread to provide said frictional braking of said railway car wheel, said opposing end walls being disposed in generally perpendicular relationship to said longitudinal centerline of said brake shoe block, and at least said first longitudinal sidewall having a longitudinal taper including a first tapered portion and a second tapered portion forming the entire extent of said first sidewall for limiting the area of said braking face along said at least said first sidewall having contact with one of the wheel flange and wheel rim when said brake shoe member is misaligned with said wheel tread to thereby adapt said braking face for engagement with said wheel tread.   
     
     
       2. A brake shoe member as recited in claim 1, wherein the taper of said first tapered portion and said second tapered portion is in opposite directions. 
     
     
       3. A brake shoe member as recited in claim 2, wherein said first tapered portion is symmetrical with said second tapered portion about a plane passing through the longitudinal midpoint of said brake shoe member perpendicular to said longitudinal centerline. 
     
     
       4. A brake shoe member as recited in claim 3, further characterized in that the lateral dimension of said braking face perpendicular to said longitudinal centerline is greatest at the longitudinal midpoint of said brake shoe member. 
     
     
       5. For frictionally braking a railway car wheel having a tread, a rim at one side of the tread and a flange at the other side of the tread, a brake shoe member comprising: (a) a backing plate to which a brake force is applied;   (b) a brake shoe block affixed to said backing plate and having first and second break shoe segments each of which comprise: (i) first and second longitudinal sidewalls disposed lengthwise on opposite sides of a longitudinal centerline of said brake shoe block;   (ii) an inner end wall at one terminus of said first sidewall adjacent a longitudinal midpoint of said brake shoe member; and   (iii) an outer end wall at the other terminus of said first sidewall disposed in generally perpendicular relationship to said longitudinal centerline of said brake shoe block, said sidewalls and said end walls delineating a braking face therebetween to provide said frictional braking of said railway car wheel, at least said first longitudinal sidewall having a longitudinal taper such that the lateral dimension of said braking face perpendicular to said longitudinal centerline decreases in a direction from said inner end wall to said outer end wall of each one of said first and second segments of said brake shoe member to limit the area of said braking face along said at least said first sidewall having contact with one of said wheel flange and said wheel rim when said brake shoe member is mis-aligned with said wheel tread to thereby adapt said braking face for engagement with said wheel tread.     
     
     
       6. A brake shoe member as recited in claim 5, wherein said longitudinal taper of said at least said first sidewall is rectilinear. 
     
     
       7. A brake shoe member as recited in claim 5, wherein said first longitudinal sidewall includes a portion thereof disposed in generally parallel relationship with said longitudinal centerline. 
     
     
       8. A brake shoe member as recited in claim 7, wherein said second sidewall is mirror image of said first sidewall. 
     
     
       9. A brake shoe member as recited in claim 5, wherein the dimension of said at least said first sidewall along said longitudinal taper is greater than the maximum lateral dimension of said braking face perpendicular to said longitudinal centerline. 
     
     
       10. A brake shoe member as recited in claim 9, wherein said longitudinal taper of said at least said first sidewall is such that the lateral dimension of said braking face perpendicular to said longitudinal centerline is greatest at a location intermediate said inner and outer end walls. 
     
     
       11. A brake shoe member as recited in claim 5, wherein said opposing end walls extend rectilinearly from said first sidewall to said second sidewall.